1 package com.twister;
 2 
 3 import java.util.ArrayList;
 4 import java.util.Collections;
 5 
 6 public class Points implements Comparable<Points>{
 7     int xCoordinate;
 8     /*
 9      * 1. Returns 0 if both points have same xCoordinate (say 3 & 3) - returns 3-3=0
10      * 2. Returns +ve if first point is on the 
11      * right hand side of the second point (say 5, -3) - returns 5 - (-3) = 8 
12      * 3. Returns -ve if first point is on the 
13      * left hand side of the second point (say -5, 3) - returns (-5) - (3) = -8
14      */
15     public int compareTo(Points p) {
16         return xCoordinate - p.xCoordinate;
17     };
18 
19     public static void main(String[] args) {
20         ArrayList<Points> arrPoints = new ArrayList<Points>();
21         /* Add lots of points to the array list */
22         Collections.sort(arrPoints);
23         /*Print the sorted collection */
24     }
25 }